Embodiments of the present invention relate to a process for establishing a data link between two processors.
Embodiments of the present invention also relate, but not exclusively, to Near Field Communication (NFC) technology as well as to NFC chipset structures, i.e., groups of chips including at least one NFC component.
These past few years, industry has greatly invested in research and development of NFC technology in order to integrate NFC controllers within portable objects, such as mobile telephones or equivalent (for example, personal digital assistants (PDAs) equipped with a mobile telephone function). This allows such portable objects to be used for payment or access control (subway, bus, or the like). Furthermore, the user is offered all the other applications of NFC technology, such as the reading of tags or of contactless cards.
Certain applications, such as payment and access control, require a higher level of security. These applications need to be controlled by a secure processor having cryptographic functions for the authentication of the user and/or of the portable object with respect to a transaction terminal. Some mobile telephones already include a secure processor, such as the processor of a Subscriber Identity Module (SIM) card.
An important industrial issue thus arose from the very beginning of NFC technology, i.e., the question of whether the security of NFC applications should be entrusted to the processor of the SIM card or to a second secure processor that would be supplied by the NFC application providers.
Various different NFC chipset architectures dedicated to telephone applications were thus envisaged, some using the processor of the SIM card to manage the NFC applications, others provided with a second secure processor, or a combination of the above two solutions. FIG. 1 shows schematically an example NFC chipset architecture using a secure processor of a SIM card to manage the NFC applications. The NFC chipset is integrated in a portable device HD1 (“Handheld Device”), for example a mobile telephone, and includes a secure processor SP1 of the SIM card, a baseband processor BBP to establish a telephone communication via a cellular telephone network, and an NFC controller designated “NFCC”, equipped with an antenna coil AC0, to receive and emit data by inductive coupling. Processor SP1 is linked to controller NFCC as a host processor by the intermediary of a data link functioning according to a specified protocol, for example the Single Wire Protocol (SWP). Baseband processor BBP is also connected to controller NFCC as a host processor, for example by an asynchronous link controlled by Universal Asynchronous Receiver Transmitter (UART) ports. If desired, processor SP1 can also be directly linked to baseband processor BBP by a bus ISO 7816.
In such an NFC chipset, secure processor SP1 ensures both the secure management of telephone connections with a cellular telephone network CNT and established by the processor BBP, and the security of NFC applications (payment, access control, or the like). During an NFC application, processor SP1 links itself to an external device NFCD by the intermediary of controller NFCC and by a contactless communication channel that controller NFCC establishes with the external device by inductive coupling.
A second secure processor can also be connected to controller NFCC as a third host processor to manage other NFC applications. Pursuant to a recent industrial agreement, it was decided that the SIM card will continue to be used to manage NFC applications, which explains the addition of an SWP port within the latest generation SIM cards, also known as “SIM-NFC” cards.
The deployment of NFC applications in mobile telephones is hindered by cost constraints. In fact, the integration of NFC controllers requires substantial modifications of the motherboards of mobile telephones, which in turn implicates considerable industrial investments and a significant increase in the cost price. Therefore, because of these factors, NFC technology remains confidential and will not be integrated within most mobile telephone models until the market demand is sufficient.
In order to offer NFC technology to the user without straining the cost price, an NFC architecture concept has been proposed that consists of “externalizing” the NFC controller by mounting it upon a support distinct from the motherboard of the telephone. This solution is schematically shown in FIG. 2. Processor SP1 and baseband processor BBP are mounted within mobile telephone HD1 and are conventionally linked by a bus ISO 7816, while the NFC controller is mounted within a distinct portable device HD2, for example a plastic card or sticker designed to be attached to the back of a mobile telephone. A contactless data link is established between processor BBP and the NFC controller, by emitters-receivers WL1, WL2 of Wifi or Bluetooth type. This contactless data link allows baseband processor BBP to be used to control NFC applications that are not secure but necessitate a large calculation power (for example, the reading of video or music files).
However, in such an NFC chipset architecture, processor SP1 of the SIM card is no longer linked to controller NFCC. A second secure processor SP2 is therefore added in device HD2. This second secure processor is connected to controller NFCC and is dedicated to NFC applications.
As the majority of mobile telephones are now equipped with an emitter-receiver of Wifi or Bluetooth type, such an NFC chipset architecture offers the advantage of not requiring any additional material cost for the fabrication of the motherboard of the mobile telephone, and only requires software.
However, the additional cost of emitter-receiver WL2 of Wifi or Bluetooth type within portable device HD2 is non-negligible, as well as the addition of the second processor SP2 to manage secure applications. The electrical consumption of emitter-receiver WL2 is also non-negligible and requires the provision, within device HD2, of a specific power source, such as a rechargeable battery and/or photovoltaic cells.